Comments on: reiserfs and dd_rescue for data recovery

By: Audrey Phillips

Audrey Phillips — Wed, 26 May 2010 01:37:05 +0000

Data Recovery is a very costly option that is why you should always check your storage media for any signs of wear and tear.,:’

By: jharris1993

jharris1993 — Mon, 14 Dec 2009 19:58:51 +0000

When running dd_rescue – don’t forget the “-r” option! (reverse copy)

What you can do is this – try it running dd_rescue the “normal” way and then – when it finishes (or hangs, or whatever) and you have bad blocks, try running the same command again with the “-r” option. It will take the same drive, the same output file, the same bad-block file, etc – and do the whole job again filling in the places where it was able to get good data.

example: A failing 20 gig partition on a 60 gig drive – copying to a file (so I can loop-mount and extract data before using the failed hard drive as a target for my 12 gage shotgun!)

Viz: dd_rescue -v -l 60gigp1log.txt -o 60gigp1bb.txt /dev/sdg1 ./60gigp1.bin

-v = verbose output (tell me a LOT about what you’re doing)
-l = name of logfile to write output to (important!)
-o = name of bad-block file – where the locations of potentially bad blocks are found (*very* important!)
/dev/sdg1 (the drive that is failing)
./60gigp1.bin = the binary “image” being made by dd_rescue.

I ran the dd_rescue command shown above, and it went through the drive about 1/3 of the way and then just bogged-down. I cancelled out with a ctl-C and re-ran the same command with “-r”

Viz: dd_rescue -r -v -l 60gigp1log.txt -o 60gigp1bb.txt /dev/sdg1 ./60gigp1.bin

It then started attacking the drive from the “other side”.

A couple of repetitions of this and I had a complete binary with no bad-blocks. Of course, I have not yet loop-mounted the binary so I don’t know what kind of trouble the actual filesystem might be in – but once you have a “clean” (or nearly clean) binary image of the partition, you are in a position to let the file system’s own recovery tools (as noted in the previous post) do their job.

What say ye?

Jim

By: Diego

Diego — Wed, 08 Aug 2007 03:43:15 +0000

Please forgive my total lack of patience, the process ended just fine:

327035 directory entries were hashed with “r5″ hash.
“r5″ hash is selected
Flushing..finished
Read blocks (but not data blocks) 103806568
Leaves among those 116376
Objectids found 324508

Pass 1 (will try to insert 116376 leaves):
####### Pass 1 #######
Looking for allocable blocks .. finished
0%….20%….40%….60%….80%….100%
Flushing..finished
116376 leaves read
116176 inserted
– pointers in indirect items pointing to metadata 7 (zeroed)
200 not inserted
non-unique pointers in indirect items (zeroed) 2984
####### Pass 2 #######

Pass 2:
0%….20%….40%….60%vpf-10260: The file we are inserting the new item (134320 14974 0xae532001 IND (1), len 4048, location 48 entry count 0, fsck need 0, format new) into has no StatData, insertion was skipped
….80%….100%
Flushing..finished
Leaves inserted item by item 200
Pass 3 (semantic):
####### Pass 3 #########
vpf-10680: The file [249620 343697] has the wrong block count in the StatData (1414608) – corrected to (1403248)
vpf-10680: The file [335046 335060] has the wrong block count in the StatData (23448) – corrected to (22904)
vpf-10680: The file [241839 243017] has the wrong block count in the StatData (64) – corrected to (56)
Flushing..finished
Files found: 285283
Directories found: 33617
Symlinks found: 4426
Others: 1167
Pass 3a (looking for lost dir/files):
####### Pass 3a (lost+found pass) #########
Looking for lost directories:
Flushing..finished
Pass 4 – finished
Deleted unreachable items 2
Flushing..finished
Syncing..finished
###########
reiserfsck finished at Wed Aug 8 13:18:34 2007
###########

No i am on a “dd if=/dev/zero of=/dev/sda bs=1M” run to the original drive and see if it can be rescued ;)

By: Diego

Diego — Wed, 08 Aug 2007 02:47:32 +0000

Dude, the dd_rescue processs has finished succesfully:

dd_rescue: (info): /dev/sdb2 (480320047.5k): EOF
Summary for /dev/sdb2 -> /dev/sda1:
dd_rescue: (info): ipos: 480320047.5k, opos: 480320047.5k, xferd: 480320047.5k
errs: 168, errxfer: 84.0k, succxfer: 480319963.5k
+curr.rate: 832kB/s, avg.rate: 9812kB/s, avg.load: -2.9%

But now i am worried about the fsck, because it has hanged at 40%, just like with the original Hard Drive:

Will rebuild the filesystem (/dev/sda1) tree
Will put log info to ‘stdout’

Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes
Replaying journal..
Reiserfs journal ‘/dev/sda1′ in blocks [18..8211]: 0 transactions replayed
###########
reiserfsck –rebuild-tree started at Wed Aug 8 08:02:26 2007
###########

Pass 0:
####### Pass 0 #######
Loading on-disk bitmap .. ok, 103818443 blocks marked used
Skipping 11875 blocks (super block, journal, bitmaps) 103806568 blocks will be read
0%….20%….40%

It hasnt finished yet, but i fear a bad outcome; if the problem is no physical is there anything i can do to fix this?

Regards my friend…

By: Diego

Diego — Mon, 06 Aug 2007 22:51:12 +0000

As always, my friend codehead to the rescue; i know this is the second time this happens to me and the second i bother you for help… You know it will also be to your benefit when we sync our multimedia collections ;)

A hug from the Land down Under!

By: Robin

Robin — Wed, 19 Jul 2006 10:50:47 +0000

It is good to see prople sharing their experinces like this which would give some knowledge about what to do in case of a possible data loss in thier system. I have seen most of the people loose thier data just because of the fact they are unaware that there is something called Data recovery with which they can recover most of their data without allmost all the files to be intact. I got my data recovered from a service provider Disk doctors Labs and after sent most of the people i sent to disk doctors gave me good and positive response

By: javier

javier — Tue, 18 Jul 2006 07:46:31 +0000

¡Saludos tocayo!

Hace un tiempo encontré tu blog, aunque lamentablemente no he tenido tiempo de seguirlo. Me ha parecido interesante por muchas cosas: tivo, mutuo interés por tecnología, somos de la misma institución (tec), tus imágenes de la misma me sirvieron mucho…

En fin, espero darme una vuelta más seguido.

javier.